Effect of environmental temperature changes on rat liver fatty acid desaturases.

Female rats warm-adapted at 30-32 C for 20-25 days and then shifted to 13-15 C for 12, 24, 48, 72 and 120 hr showed that delta 9 desaturase and fatty acid synthetase activity decay after 24 hr of cold exposure, while delta 6 and delta 5 desaturases were increased after this period of time. These results were confirmed by an increase of arachidonic acid of heart and liver microsomes phosphatidylcholine and a decrease of oleic acid. Neither NADH-cyt b5 reductase nor NADH-cyt c reductase activity of liver microsomes were significantly affected. Male rats warm-adapted under the same conditions and then shifted to 13-15 C for 120 hr did not show significant changes in fatty acid synthetase, delta 9 and delta 6 desaturases and enzymes of the microsomal electron transport chain. Therefore, the desaturase response to environmental temperature changes could be plausibly linked to female hormones.